Monoamine oxidase inhibition and the induction of ponto-geniculo-occipital wave activity by reserpine in the cat

Abstract

Reserpine induces ponto-geniculo-occipital wave activity similar to that seen in the cat during the rapid eye movement phase of sleep. This action of reserpine was blocked by the monoamine oxidase inhibitors, pheniprazine, harmaline and clorgyline, but not deprenyl or its demethylated analog. After a single dose (20 mg/kg) of either pheniprazine or harmaline, the time course of antagonism of the effect of reserpine was in good correspondence with inhibition of monoamine oxidase but not with restoration of the serotonin content of several regions of the brain. Harmaline had a reversible effect while that of pheniprazine persisted for weeks. Clorgyline in low doses (0.5-1.0 mg/kg), at which it is a specific inhibitor of type A monoamine oxidase, antagonized the action of reserpine for over 2 weeks. Deprenyl and its demethylated analog failed to suppress the reserpine-induced waves even at 10 times the dose of clorgyline when they should have completely inhibited type B monoamine oxidase. In contrast to antagonism of reserpine, suppression of rapid eye movement sleep by these monoamine oxidase inhibitors could be temporally dissociated from their inhibition of the enzyme. It is concluded that suppression of the induction of ponto-geniculo-occipital waves by reserpine after administration of the monoamine oxidase inhibitors is a specific effect of these drugs and is related to inhibition of type A monoamine oxidase. Suppression of rapid eye movement sleep is probably a nonspecific effect and not related to inhibition of the enzyme.